<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
</head>
<body>

  <div id="app">
    姓：<input type="text" v-model="firstName"><br>
    名：<input type="text" v-model="lastName"><br>
    <p>姓名：{{fullName}}</p>
    <button @click="changeName">修改姓名</button>
  </div>
  <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
  <script>
    const app = new Vue({
      el: '#app',
      data: {
       firstName:"张",
       lastName:"三"
      },
      computed: {
        // 简写
          // fullName() {
          //   return this.fristName + this.lastName;
          // },
        fullName:{
          get(){
            return this.firstName + this.lastName
          },
          set(value){
          console.log("修改-fullName被重新赋值", value);
            
           this.firstName=value.slice(0,1)
           this.lastName=value.slice(1)
          }
        }

      },
      methods: {
        changeName(){
          this.fullName="李四"
        }
      }
    })
  </script>
</body>
</html>